臺灣博碩士論文加值系統

隨著無線通訊科技的發展與進步，有越來越來的行動裝置，支援多種的無線通訊技術，其中最常見的技術為3G行動通訊網路和Wi-Fi無線網路。另外隨著無線網路頻寬的增加，多媒體群播服務的應用也從乙太網路擴展到無線通訊網路上。因此我們可以得知，未來的行動裝置將會存在支援多種無線通訊技術的異質網路，以及越來越使用者在移動的過程中透過行動裝置取得多媒體群播服務。
為了讓行動裝置可以在眾多的無線網路基地台中取得多媒體群播服務，我們設計了一套在行動裝置上的以情境感知為基礎的換手機制包含了系統偵測、換手決策以及換手執行，讓行動裝置可以根據目前網路的環境，以及使用者的多媒體群播服務，自動的選擇合適的無線網路做連線。行動裝置在移動的過程中，可以自動的尋找適合行動裝置目前的網路連線做切換，包括了切換不同網路的垂直換手或是在Wi-Fi網路的水平換手，不會因為移動的關係，使得原有的連線訊號品質過低，而造成連線中斷。
另外為了讓行動裝置可以在不同的無線環境中，取得多媒體群播服務，我們也設計了一個群播移動的管理機制，透過群播代理伺服器(MA)的協助，讓行動裝置可以在不支援IP群播的環境中，取得多媒體群播服務。

With the progress and development of wireless technology, mobile devices now support a variety of wireless protocols, allowing them to connect to 3G mobile and Wi-Fi wireless networks. With the addition of more wireless network bandwidth, multicast multimedia services have been applied from wired networks to also wireless networks. Therefore we can see that future mobile devices shall support multiple wireless technologies and allow users to receive multicast multimedia transmissions through homogeneous or heterogeneous networks while they are moving.
In order for mobile devices to roam through wireless networks and receive multicast packets from different base stations, we have designed a context-aware based handoff scheme for mobile devices. This scheme includes system discovery, handoff decision, and handoff execution operations. Mobile devices shall receive multicast multimedia services by choosing the most suitable wireless protocol to connect to the wireless network, depending on in what environment the mobile device is in. When the mobile device leaves this network, it may perform vertical or horizontal handoff operations to switch connection to a heterogeneous wireless network or homogeneous wireless network, respectively.
In addition to enable mobile devices to receive multicast multimedia services in heterogeneous networks, we have designed a mobility management mechanism. This management mechanism shall allow mobile devices to receive multicast transmissions through Multicast Agents (MA), that shall be of assistance to the foreign network, if IP multicast mobility is not supported there.

誌謝辭 I
中文摘要 II
Abstract III
目錄 IV
圖目錄 VII
表目錄 X
第一章 序論 1
1.1 研究背景 1
1.2 研究動機 1
1.3 研究目的 2
1.4 研究方法 2
1.5 論文架構 3
第二章 背景介紹與相關研究 4
2.1 背景介紹 4
2.1.1 IP multicast 4
2.1.2 IGMP協定 6
2.1.3 Wi-Fi網路 8
2.1.4 3G網路 10
2.1.5 SNMP簡單網路管理協定 13
2.2 相關研究 16
2.2.1 換手機制 16
2.2.2 水平換手 17
2.2.3 垂直換手 18
第三章 以情境感知為基礎的換手機制與群播連線管理 21
3.1 網路環境假設 21
3.2 網路元件假設 22
3.2.1 U-Gate 22
3.2.2 Multicast Agent (MA) 23
3.2.3 Mobile IP 24
3.2.4 Access Point (AP) 24
3.3 以情境感知為基礎的換手機制 25
3.3.1 System Discovery 25
3.3.2 Handoff Decision 28
3.3.3 Handoff Execution 36
3.4 移動群播連線管理機制 37
第四章 系統設計與實作 44
4.1 Network Monitor的設計與實作 44
4.1.1 NM設計概念 44
4.1.2 NM實作環境 44
4.1.3 NM系統實作 45
4.1.4 NM運作 48
4.2 Intelligence Handoff Software的設計與實作 49
4.2.1 IHS設計概念 49
4.2.2 IHS實作環境 49
4.2.3 IHS系統實作 50
4.2.4 IHS運作 54
4.3 網路環境 56
4.4 系統運作流程 58
第五章 系統測試 65
5.1 測試環境建置 65
5.2 NM系統測試 66
5.2.1 NM使用SNMP取得AP的資訊 66
5.2.2 NM偵測網路上的群播服務 68
5.3 IHS系統測試 69
5.3.1 換手決策的觸發 69
5.3.2 換手決策的驗證 74
5.3.3 執行換手 78
5.3.4 3G群播服務 80
5.4 效能分析 84
5.4.1 測試環境和參數設定 85
5.4.2 Wi-Fi網路的水平換手測試 86
5.4.3 垂直換手測試 93
第六章 結論 96
6.1 研究結論 96
6.2 研究貢獻 97
6.3 後續研究方向 97
參考文獻 99

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